Blister packaging offers many advantages to the industry and to the public, and the machinery will continue to support this proven form of pharmaceutical packaging. Improvements in the form, materials, and machinery for blister packaging will continue to increase the applicability of this method for containing and distributing pharmaceutical products. Figure 1 shows an example of a blister packaging machine.

 The sequence involves :
  • heating the plastic
  • plastic thermoforming into blister cavities
  • loading the blister with the product
  • placing lidding material over the blister
  • heat-sealing the package
 There are 2 main types of blisterpacking machine :
  1. the continuously operating line
  2. the intermittently operating line

Continuously Operating lines

Advantage: equipped with sealing rollers, is that they can achieve higher output.
Disadvantage: the heat-sealing process must be performed at higher temperatures; 200-300°C. This means that the packaging material is subjected to more stress and higher strains.

Operating Process of Continuously Operating lines Blister Machine

With the following exceptions, the stations of the continuously operating machine function similarly to the stations of the intermittently operating machine:
  • The unwinding station continuously supplies forming films and lidding materials.
  • The stretching station follows the quality control station. With continuously operating machines, the eye-mark distances for the lidding material are sensed immediately after the unwinding station. Then the lidding material is stretched appropriately for the machine's speed.
  • The sealing station on continuously operating machines is equipped with sealing rollers. The sealing temperatures range between 200 and 300°C.
In the course of this process, the lidding material is continuously sealed onto the forming film for the goods to be packaged.

Operating Process of Intermittently Operating Lines Blister Machine

Advantage: Intermittently operating systems work with sealing plates, and the sealing temperature can be relatively low: 140-200°C. Sealing with plates permits the use of larger widths of forming films and lidding materials because a more constant sealing effect can be expected.

Disadvantage : Intermittent processes tend to have slower operation, therefore slower output. Intermittent equipment also tends to require more maintenance because of the stop-and-start nature of the operation.

Detailed assembly. Blister packaging machines typically operate with intermittent motion. The seal is made during the dwell time required for thermoforming. The essential parts and functions of an intermittently operating packaging machine include the following.
  • The unwinding station.The unwinding station supplies the forming films and the lidding material at a rate corresponding to the speed of the packaging machine (see Figure 1, part A).
  • The heating station. The heating station raises the temperature of the plastic forming films to a level suitable for deep drawing. Forming films containing the polyvinyl chloride (PVC) support material are heated to 120–140 8C. Polypropylene (PP) forming films are heated to 140–150 8C. Forming films containing aluminum are not heated before the forming process (see Figure 1, part B).
  • The forming station. The forming station forms the plastic blister cavities via compressed air or die plates. Films containing aluminum are formed with mechanical forming tools only (see Figure 1, part B).
  • The cooling station. The cooling station cools PP films after the forming process. There is no need to cool laminates containing PVC or aluminium.
  • The feeding machine.The loading area fills the blister cavities with product. The feeding machine can be linked, or the product to be packaged can simply be swept into the blisters (see Figure 1, part C).
  • The quality control station detects flaws that have occurred in the packaging process. After punching, these packages are rejected and scrapped.
  • The sealing station. The sealing station heatseals the lidding material to the forming film that contains the product (see Figure 1, part D).All heat-sealing methods mate the blister and lid under constant pressure for a specified time, during which heat is supplied. The mating surfaces fuse and bond, setting almost instantaneously when heat input stops. Depending on the type of machine, the sealing temperature typically ranges between 140 and 340 8C.
  • The cooling station. The cooling station is necessary with all forming films (see Figure 1, part D). PP forming films must be cooled longer than other types of film. The index station is a component only of machines that are controlled by a feeding mechanism. This device senses the eye-mark distances on the lidding material and thus governs the speed of the machine. This kind of control can operate satisfactorily only within very close eye-mark tolerances.
  • Labeling through packaging. Packages are labeled, notched, and then marked with a batch number at the coding station. The perforating device makes a cross-shaped perforation along the sealing seams.At the punching station, the packages are then separated into sheets that typically contain from 10 to 20 individual blisters. The vision system checks the filled packages for defects. Finally, a multipacking machine packs the individual packages into bigger cartons.

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